US2152348A - Telepicture recording system - Google Patents

Description

March 28, 1939.

w. G. H. FINCZH 2,152,348

TELEPI CTURE RECORDING SYSTEM Filed Aug. '7, 1936 4 Sheets-Sheet l TRANSMITTE R o RECEIVER INVENTQR William ATTORNEY March 28, 1939. w H F|NCH 2,152,348

TELEFICTURE RECORDING SYSTEM Filed Aug. 7, 1936 4 Sheets-Sheet 2 INVENTOR wiuiam gz r fi'mh j BY ATTORNEY TELEPICTURE RECORDING SYSTEM Filed Aug. '7, 1956 4 Sheets-Sheet 3 INVENTOR ATTORNEY W. G. H. FlNCH March 28, 1939.

TELEPICTURE RECORDING SYSTEM Filed Aug. '7, 1956 4 Sheets-Sheet 4 Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE Application August 7,

6 Claims.

This invention relates to telepicture systems and more particularly relates to novel methods of and apparatus for electro-optically reproducing pictures and high fidelity recording of the shaded characteristics of the pictures.

It is among the objects of my present invention to provide a simple electro-optical telepicture recorder for translating picture modulated signals into correspondingly shaded reproductions; to provide a light weight compact electro-optical recording unit of rugged design; and to provide a highly efficient picture reproducer employing a constant intensity light source.

Electro-optical recording systems of the prior art comprised light valves employing shutters or strings actuated by the signal currents to vary the amount of light passing the shutters. Such light valves had a comparatively low sensitivity and accordingly required high signal intensities for their operation. The recording system of my present invention employs a sensitive galvanometer which actuates a reflecting mirror and is extremely sensitive in operation. Accordingly, another object of my invention is to provide an efficient and sensitive electro-optical recording system,

Prior recording systems employing a galvanometer actuated deflecting mirror were not adaptable for high definition recording, that is, the tonal range of the shading was either black and white or one or two intermediate shades therebetween. My present invention employs an optical system controlled by the deflecting mirror for reproducing a wide shading reproduction range proportional to the modulation of the received signals. Accordingly, it is a further object of my present invention to provide a wide range picture shading reproduction system.

The electro-optical reproducing system of my present invention is adapted to record by either a variable line width or variable density system of shading reproduction. A square light beam is normally directed at a corresponding square aperture and passes on to a revolving light sensitive sheet. The telepicture signals cause a deflecting mirror to deflect the beam with respect to the aperture and permit varying percentages of the beam to be passed through the aperture in proportion with the intensity of the telepicture signals. By deflecting the beam in a plane parallel to the scanning direction, a reproduction by variable density recording is had, and by deflecting the beam in a plane perpendicular to the direction of scanning, variable line width recording is had. It is accordingly another object of my 1936, Serial No. 94,730

present invention to provide a novel electro-optical system for variable line width or variable line density recording.

These and other objects of my present invention will become apparent in the following description taken in connection with the drawings in which:

Figure 1 is a schematic illustration of a telepi'cture transmitting system.

Figure 2 is a schematic illustration of a preferred embodiment of a telepicture recording system in accordance with my present invention.

Figures 3A, 3B and 3C are diagrammatic representations for illustrating variable line density recording by my present invention.

Figures 4A, 4B and 4C are diagrams for illustrating variable line width recording by my present invention.

Figure 5 is a vertical cross-sectiona1 illustration through a preferred embodiment of a telepicture recording apparatus constructed in accordance with my present invention.

Figure 6 is a horizontal cross-sectional view taken along 6-6 of Figure 5 through the electrooptical recording unit.

Figure 7 is an end view of the deflecting mirror suspension system viewed from l-'l of Figure 5.

Figure 8 is an end view of the light source condensing lens system and corresponding aperture as viewed from 8-8 of Figure 5.

Figure 9 is an end view of the second square aperture as viewed from 9-9 of Figure 5.

Figure 10 is a cross-sectional view taken through Hl-l0 of Figure 5 illustrating the last of a series of square apertures, this aperture coacting with the deflecting light beam to produce the optical shading modulations.

My present invention may be used with any type of telepicture transmitter and in Figure 1 I have schematically illustrated such a transmitter. The picture ID to be transmitted is mounted upon a drum H which is rotated at a predetermined rate and simultaneously moved axially with respect to the point of light [2 focused thereon to provide a successive scanning action as is well known in the art. A source of light [3 is focused upon the point I2 by a lens system I4. Light is reflected from the picture l0 and collected by lens system l5, and focused upon the photoelectric cell l6 which translates the varying light intensity impinged thereon to electric signals proportional to the shading of the picture ID. A radio frequency transmitter IT is shown connected to the photo-electric cell It for transmitting over antenna l8, carrier modulated signals in a manner well known in the art. The telepicture signals may be transmitted by other mediums such as direct wire connections over telephone systems and the like.

Figure 2 is a schematic illustration of a preferred form of recording system according to my present invention. Antenna l9 introduces the radiated signals from transmitter I"! to receiver unit 20 which amplifies and rectifles the telepicture signals. The output of receiver 26 is con nected to the movable coil 2| of galvanometer unit 22. A small mirror 23 is cemented upon the outside face of coil 2i. Coil 2| is pivotally mounted between the opposite poles 24 and 25 01' the permanent magnetic structure 2'5 oi galvanometer 22. An electro-magnet 2'! is wound on magnet structure 28 and connected to a direct current source of potential to provide uni-directional magnetic field between the opposed pole faces 24-25 and across the movable coil 2 I. The varying intensity telepicture signals introduced to coil 2| will cause the coil to deflect from its normally mechanically biased position to an ex tent proportional to the intensity of the signals. The mirror 23 attached to the galvanometer coil 21 will correspondingly deflect a light beam directed upon it.

The recording unit schematically illustrated at 30 comprises a constant source of light 3| such as a small exciter lamp connected to direct current energization. An opaque screen 32 is placed in the path of light from source 3| and a square aperture in screen 32 permits a square beam. of light to pass therethrough to the condensing lens 33 and on. to a second opaque screen 34 containing a smaller square aperture. The square beam 35 passing through the aperture of screen 34 impinges upon surface 36 of a 180 reflecting prism 31 where it is deflected from its path to the opposed surface 38 which further deflects the beam 90 as incident beam 39 impinging upon mirror 23.

The prism 31 and the associated components for producing the incident light beam 39 are inclined at a small angle to the vertical so that the reflected beam 40 from the mirror will clear the bottom edge containing surface 38 of the prism. 31 and pass on to a final opaque screen 4| containing a square aperture. The beam passing through the aperture of screen 4| is condensed by the objective lens system 42 projecting from recording unit 30 to a small square spot 43 upon a light sensitive sheet 44 mounted upon recording drum 45. The galvanometer system 22 is preferably inclined at half the angle of inclination of the prism 31 with respect to the vertical so that the normal reflected beam 40 will be horizontal as will be the condensed beam 46 emanating from the objective lens system 42. The receiver drum 45 is rotated and moved axially in phase synchronism with the corresponding transmitter drum II in any manner known to those skilled in the art. Since the method for synchronizing the transmitter and receiver forms no part of my present invention, the present disclosure is not concerned with this phase of the system. I prefer to employ a synchronizing system such as disclosed in my Patent No. 2,047,863, which issued July 14, 1936, entitled Telecommunications system.

The deflection of mirror 23 in accordance with the picture signals causes the reflected square light beam 40 to move across the aperture 41 of screen 4| to produce the picture shading or tonal values upon the recorded picture 44 as follows:

Figures 3A, 3B and 3C are diagrammatic illustrations of the variable line density recording modification of my present invention. Figure 3A represents the undeflected position of mirror 23 wherein the maximum amount of the reflected square beam 49 passes through the aperture 41 of opaque screen 4| and corresponds to the position illustrated in Figure 2. The objective lens system schematically shown at 42 concentrates the beam 48* transmitted across aperture 41 upon the light sensitive film 44 as a square spot of light 43, the dimensions of which have been exaggerated for illustrative purposes. The line of scanning 48 bounded by the parallel dotted lines represents a scanning line on the recorded picture. This line in my preferred embodiment is .01 inch wide, corresponding to a picture definition of lines per inch. The corresponding size of the square spot 43 is .01 inch in width by .01 inch in height, when the reflected beam 40 is fully incident upon aperture 41. The scanned area 5|! on the light sensitive sheet 44 is ailected by the light spot 43 to a maximum degree since a maximum of light is incident upon the film 44. The electro-optical system is preferably designed so that the adjacent scanned lines corresponding to 5|] are contiguous so that a smooth reproduction of a picture is produced having substantially no visible spacings between the scanning lines to avoid a striped or typically loosely scanned facsimile. The rate of the transverse movement 01 the film with respect to the light spot should correspond to the width of the light spot 43 which in the present example is .01 wide to correspond to a transverse scanning rate of .01 per revolution. The aperture 47 may have a dimension of .15 inch by .15 inch, the condensing lens system 42 contracting the square spot to the requisite dimensions of .01 by .01.

When a picture signal causes the mirror 23 to be deflected from its normal position as illustrated in Figure 3B, the reflected beam 40 from mirror 23 is not wholly incident upon aperture 45 and a portion of the beam 49 passes through aperture 41, the proportion of the light 49* corresponding to the amount of deflection of mirror 23 which in turn depends upon the relative picture signal intensity. The condensing lens 42 concentrates the beam 43 impinging thereon to a rectangular spot 43 upon the light sensitive film 44. The area of spot 43 is .01" wide, corresponding to the normal width of scanning, but the height of the spot is proportional to the signal intensities actuating the deflecting mirror 23. Since the intensity of the constant light source 3| is kept substantially constant, the shading of the scanning area 58 will be intermediate between white and black in the ratio of the deflection of the mirror 23 from normal as will now be evident to those skilled in the art. Since the rate of movement of the light sensitive sheet 44 past the focused light spot 43 is constant and at a predetermined rate, the corresponding shading or tonal value or" the exposed area will be proportional to the height of the light spot impinged upon the fllm and which, in turn, corresponds to the ratio of the transmitted light 4|) to the incident light 4|] upon aperture 41.

Figure 3C represents the deflection of mirror 23 to an amount causing zero transmission of light through aperture 41 since the reflected beam 40 is moved past the aperture. No light will accordingly pass through the objective lens system 42 or upon the light sensitive sheet 44 and an unaffected line of scanning 48 will result correu .section 50.

sponding to the white area illustrated at 50.

It is to be understood that the deflection of.

mirror 23 is in proportion to the picture signal strength and the corresponding recorded shading ranges proportional between black and white to faithfully record the intermediate shadings as a variable line density system. This system is efiected by deflecting the light beam in a plane parallel to the scanning direction 48 as will now be understood.

Variable line width recording is effected by the apparatus of my present invention by merely orienting the galvanometer 22 in a direction perpendicular to that illustrated in Figures 2, 3A, 3B and 30. By deflecting the mirror 23 in a plane at right angles to the scanning direction, the variable line width recording is performed as illustrated in Figures 4A, 4B and 40. Figure 4A corresponds to Figure 3A in that the reflected beam 48 is wholly incident upon aperture 41 of opaque screen 4|. The condensing lens system 42 concentrates the square beam as a square light spot 40 upon the sensitive film 44'. The scanned direction of Figure 4A is shown perpendicular to the scanning direction of Figure 3A. The scanned area 5i! is a scanning line of full Width, namely .01" wide due to the full incidence of the beam upon aperture 41. An adjacent scanned line 5| is shown having a similar full width and full intensity of exposure corresponding to the similar portion 550 produced by the normal position of the mirror 23.

Figure 4B is a diagrammatic illustration of the mirror 43 deflected from its normal position to correspondingly deflect the reflected beam 4% as shown so that a proportional part of the refiected beam is transmitted through the fixed aperture 41 as beam 40 The objective lens system 42 concentrates the beam on a correspondingly reduced light spot 43 shifted to one side of the scanning section schematically defined by adjacent parallel dotted lines. The smaller rectangular spot of light 43 produces a corresponding thin exposed line within the A similar reduced width line exposure is illustrated by the line The unit intensity of the light spot 43 is substantially unaffected so as to produce exposure of substantially the same intensity per unit area. However, the shading variations on the resultant picture are effected by the varying width of the constant intensity beam in a manner well known in the art. The width of the beam at any area corresponds to the intensity of the telepicture signal which, in turn, varies with the shading or" the picture being transmitted.

Figure 4C is a diagrammatic illustration of a deflected position of mirror 23 corresponding to the total obscurance of the reflected beam 40 from the sensitive film 44. The adjacent scanning line sections 50 on the film 4-4 are correspondingly unexposed, the dashed parallel lines being used merely for illustrative purposes and are actually non-existent on the film.

It is to be understood that the light sensitive film 44 may be a bromide paper for producing positive pictures or film for producing negatives. The corresponding sense of the modulation, 1. e., the maximum telepicture signal intensity corresponding to black or White picture segments is predetermined in accordance with principles well known in the art in conjunction with the sense of the deflection of mirror 23 from normal by the picture signals to produce the required type of reproduction-on the sensitive film 44 employed.

The electro-optical arrangement of my present invention permits a simple and compact arrangement of the recording unit. Figure 5 is a vertical cross-sectional view taken through the optical axis of a preferred physical embodiment of the recording unit of my present invention. Exciter lamp 52 having a compact filament 53 generates a source of light which passes through a square aperture 5& and a condensing lens 55 onto a further square aperture 55 to the 180 reflecting prism 51'.

Figure 8 is an elevational View of the condensing lens system 55 and its supporting structure.

The square aperture 54 is made in the member H2 into which the condensing lens 55 is supported. The rectangular member H2 is supported at an angle to the vertical by bracket 55 as shown in Figure 5. Figure 9 is an end view of the second aperture 55 as viewed from 99 of Figure 5, illustrating the square opening arranged in a position similar to that of the first square aperture 54.

The successive apertures 54 and 55 together with the condensing lens 55 produce a square spot of light directed upon the surface 53 of prism 51 which deflects the beam 90 to the op posed surface 59 of the prism, which further deflects the beam 90 on to the deflecting mirror Ell mounted on the diaphragm plate 5! in a manner to be hereinafter described.

The aperture 54 and condensing lens 55 together with the aperture 55 and 189 reflecting prism 51 are mounted at an inclined angle with respect to the vertical in order that the beam of light reflected from mirror 6% will clear the bottom edge of the surface 59 of prism 51 so as not to interfere with the beam of light projected to the sensitive film 62. It is preferable to cause the reflected beam 63 to be horizontal. The electro-optical system is therefore tilted to produce a resultant horizontal beam 53. The oscillograph unit 54 is tilted at half the angle to the vertical that this prism 5"! is tilted so as to effect the horizontal disposition of the resultant beam 63 as will be evident to those skilled in the art.

The aperture 54 and condensing lens 55 are secured to a movable bracket E5 attached to frame portions 66 by screws '51. Bracket 85 contains a slot 68 permitting adjusting of the condensing lens 55 along the beam for suitable focusing thereof.

The reflected beam 63 is normally directed upon a square aperture 193 set in a metal plate H. The beam 63 passing through the aperture 16 is directed upon the sensitive film 62 by the objective lens system T2. The square aperture ill preferably has the dimension of .15" x .15 and the beam 53' passing therethrough is contracted by the objective lens system 12 to a square spot .01" x .01" on film 62, if 100 scanning lines per inch are employed.

The objective lens system i2 is secured to a tube 13 attachable to one side 14 of the enclosure 15 of the recording unit. Objective lens system 12 has a threaded engagement with the tube 13 in order to adjust the distance of the objective lens system 12 and of the aperture 16 with respect to the deflecting mirror 60. The. disk ll containing aperture 10 is mounted in a cylindrical block 16 having a central opening within which is set a spring TI maintained in compression to mechanically bias the block 16 and the engagement of the objective lens system I2 with tube I9 to maintain any predetermined adjustment of these components of the electro-optical system.

Figure 10 is a cross-sectional view taken along l9--I9 of Figure 5 illustrating the small square opening 19 in opaque disk II set into one end of cylindrical box I6 slidably set Within the tube 13.

The oscillograph 64 contains a field coil I1 which is energized by direct current to produce a magnetic flux across the poles I9, through the plate 6| around the magnetic housing 19 and back to the central core 89.

A glass window 8| is mounted in the front face of the oscillograph unit 64 to prevent dust from entering therein. The plane glass window BI is inclined to the vertical as illustrated to deflect any reflected rays below the aperture 19 to prevent any extraneous light from entering aperture 19 and distorting the reproduction on the film 62.

The electro-optical recording unit 82 is mounted upon a movable bed 83 by bracket member 84. Movable bed 83 is secured to base 84. Recording unit 82 is adjustable towards or away from the film 62 by thumb screw 85 operating on screw member 86 co-acting with a threaded portion 81 of the movable bed 83. The base 84 of the recording unit 82 is mounted upon member 99 which is driven transverse of the rotated drums upon which film 92 is mounted by means of a worm screw 9|.

It is to be understood that the recording unit 82 of my present invention may be employed with any type of scanning system. In my preferred arrangement, the scanning system disclosed in my co-pending application Serial No. 84,426, filed June 10, 1936, entitled Telepicture scanning systems, is employed, and the member 99 co-acting with worm screw M is described therein in full detail.

The electrical connection of the components within the housing 15 of recording unit 62 is made to the terminals 93 on the back face 94 of unit 82. These connections are for the exciter lamp flla ment 53, the direct current field winding 11, and the windings 95 on the poles I8 connected to the telepicture signals.

Figure 6 is a horizontal cross-sectional view taken along 6-6 of Figure 5. The oscillograph unit 64 is shown with the two poles 18 projecting from the central pole 80. The outer ends of pole 18 are tapered to co-act with the metallic rectangle 96 upon which the mirror 69 is cemented. The signal coils 95 are wound about the poles 18. The telepicture signals flowing through the coils 95 vary the uni-directional magnetic field across the gaps between the poles I9 and the metallic rectangle 96 and cause the metallic member 96 to deflect in accordance with the instantaneous intensity and polarity of the telepicture signals.

Figure 7 is an end elevational view of the metallic disk 6| containing the suspended mirror 69. The metallic rectangle 96 upon which mirror 60 is cemented, was originally part of the square disk 6| and was cut out therefrom along the lines 91 and 98. A series of small drill holes 99 were first made in disk 6| and the cut outs 91 and 98 were made between the holes to produce the metallic rectangle 96 together with the suspension ribbons I99. The disk 6| is made of magnetic material so as to permit the magnetic flux to pass therethrough and to also permit efilcient deflection of the metallic rectangle 96 containing the deflecting mirror 69. A series of holes I II in the corners of the square disk 6I serve as accurate positioning means for the disk with respect to the body of the galvanometer since the screws passing therethrough clamp it into proper position.

The position of the oscillograph unit 64 is horizontally adjustable by means of the opposed set screws IM and I92. This adjustment is made to center the reflected beam 63 upon the aperture I9.

The exciter lamp 52 is adjustable both vertically and horizontally to place the filament 53 in proper position in the electro-optical system. Set screws I93 and I94 permit horizontal adjustment of the base I95 upon which exciter lamp 52 is mounted. Vertical adjustment of the lamp 52 is provided by means of the threaded screw member I96 co-acting with base I95 and operated through the head I91 of the screw I96. The shank I98 of the screw member is rotatably supported in a bracket I99 and is set against vertical movement by a collar II9. Rotation of threaded screw I96 correspondingly vertically moves exciter lamp 52 upwards or downwards according to the sense of rotation.

In the preferred embodiment corresponding to Figures 5 and 6, the beam is deflected in a plane perpendicular to the scanning direction and corresponds to the variable line width recording system described hereinabove in connection with Figures 4A, 4B and 40. It is to be understood that the identical apparatus illustrated and described may be used for variable line density recording corresponding to the disclosure in connection with Figures 3A, 3B and 30 by changing the position of the galvanometer as illustrated in Figures 5 and 6 by 90 so that the plane of deflection of the reflected beam 63 is parallel to the direction of scanning and corresponds to the schematically illustrated recording system of Figure 2. The variable line density scanning system may be equally well effected by using the electro-optical system exactly as described and illustrated in Figures 5 and 6 by changing the direction of scanning motion of the film 62 90' to that illustrated. It is to be understood that my present invention is equally applicable to either system of recording; the variable line density recording making possible a homogeneous reproduction wherein adjacent scanning lines are contiguous; the variable line width recording making evident the striations due to the variable width between adjacent scanning lines.

Although I have described a specific electrooptical circuit utilizing a moving coil or movable plate galvanometer, it is to be understood that a string galvanometer upon which a mirror is cemented or a piezo electric type of galvanometer or any other type of galvanometer movement may be substituted for the galvanometers described, without departing from the spirit or scope of my present invention. Various modifications may be made by those skilled in the art and accordingly, I do not intend to be limited except as set forth in the following claims.

I claim:

1. In a telepicture recorder: means for produc ing a square light beam having a predetermined width comprising an exciter lamp, a square aperture, a condensing lens, and prism means for reflecting said beam degrees; a disc having a square opening; means for reflecting said square light beam through said opening including a mirror; said aperture, condensing lens and prism means being inclined at an angle with respect to said disc for preventing interference of the reflected beam with the beam producing means, the dimensions of said opening being substantially equal to that of said reflected beam section; means for deflecting said mirror in accordance with received telepicture signals for passing correspondingly variable sections of said reflected light beam through said opening; means for condensing the light passing through said opening into a light spot upon a light sensitive record sheet; and means for scanning said light spot across said sheet.

2. In a telepicture recorder: means for producing a square light beam having a predetermined Width comprising an exciter lamp, a square aperture, a condensing lens, and means for reflecting said beam degrees; a disc having a square opening; means for reflecting said square light beam through said opening including a mirror, said square light beam being projected upon said mirror at an angle inclined to the normal to said disc for preventing interference of the reflected beam with the beam producing means, the dimensions of said opening being substantially equal to that of said reflected beam section; means for deflecting said mirror in accordance with received telepicture signals for passing correspondingly variable sections of said reflected light beam through said opening comprising a galvanometer; means for condensing the light passing through said opening into a light spot upon a light sensitive record sheet including an objective lens system; and means for scanning said light spot across said sheet in a direction parallel to the plane of deflection of said light beam whereby variable line density recording is effected.

3. In a telepicture recorder: means for producing a square light beam having a predetermined width comprising an exciter lamp, a first square aperture, a condensing lens, a second square aperture, prism means for reflecting said beam 180 degrees; an opaque disc having a square opening; means for reflecting said light beam through said opening including a mirror, said apertures, condensing lens and prism being inclined at an angle with respect to said disc for preventing interference of the reflected beam with the beam producing means, the dimensions of said opening being substantially equal to that of said reflected beam section; means for deflecting said mirror in accordance with received telepicture signals for passing correspondingly variable sections of said reflected light beam through said opening comprising a galvanometer; means for condensing the light passing through said opening into a light spot upon a light sensitive record sheet including an objective lens system; and means for scanning said light spot across said sheet in a direction perpendicular to the plane of deflection of said light beam whereby variable line width recording is eflected.

4. In a telepicture recorder: means for producing a beam of light having a predetermined crosssectional area comprising an exciter lamp, a light aperture, a condensing lens and an element for deflecting said beam 180 degrees; an opaque disk having an opening with dimensions substantially equal to the area of the resultant light beam; means for reflecting said light beam through said opening; said condensing lens, aperture and deflecting element being inclined at an angle with respect to said opaque disk for preventing interference of the reflected beam with the beam producing means; and means for variably deflecting said reflecting means in accordance with received telepicture signals for passing corresponding variable sections of the reflected light beam through the opening in said disk.

5. In a telepicture recorder: means for produc ing a beam of light having a predetermined crosssectional area comprising an exciter lamp, a light aperture, a condensing lens; an opaque disk having an opening with dimensions substantially equal to the area of the resultant light beam; and means for reflecting said light beam through said opening; an element for reversing the direction of the original generated beam and directing it upon said reflecting means; said condensing lens, aperture and deflecting element being inclined at an angle with respect to said opaque disk for preventing interference of the reflected beam with the beam producing means; and means for variably deflecting said reflecting means in accordance with received telepicture signals for passing corresponding variable sections of the reflected light beam through the opening in said disk.

6. In a telepicture recorder: means for producing a beam of light having a predetermined crosssectional area comprising an exciter lamp, a light aperture, a condensing lens; an opaque disk having an opening with dimensions substantially equal to the area of the resultant light beam; and means for reflecting said light beam through said opening; a prism element for reversing the direction of the original generated beam by 180 degrees and spaced from said original beam and directing the deflected beam upon said reflecting means; said condensing lens, aperture and deflecting element being inclined at an angle with respect to said opaque disk for preventing interference of the reflected beam with the beam producing means; and means for variably deflecting said reflecting means in accordance With received telepicture signals for passing corresponding variable sections of the reflected light beam through the opening in said disk.

WILLIAM G. H. FINCI-I.

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